Process for developing or peeling alkali-type photosensitive film and apparatus used therein

ABSTRACT

A developing or peeling solution for developing or imagewisely peeling an alkali-type photosensitive film containing a suspension of released photosensitive film is regenerated by introducing one or more reagents and a gas for depositing the suspension in floating state and removing the floated deposit by a skimmer from the developing or peeling solution. The regenerated developing or peeling solution can be used again and again for the development or peeling.

BACKGROUND OF THE INVENTION

This invention relates to a process for developing or peeling analkali-type photosensitive film and an apparatus used therein. Moreparticularly, this invention relates to a process for regenerating adeveloping or peeling solution for alkali-type photosensitive filmcomprising depositing a suspension of photosensitive film released andcontained in the developing or peeling solution in floc state andremoving the flocculated floating deposit from the developing or peelingsolution for reuse and an apparatus used therein.

Heretofore, development or peeling of alkali-type photosensitive filmhas been conducted batch-wise or continuously by dipping and alkali-typephotosensitive film in a several percent alkaline solution or spraying aseveral percent alkaline solution over the alkali-type photosensitivefilm. During the development, unexposed portions of the alkali-typephotosensitive film become a suspension in a suspended state in thedeveloping solution. During the peeling, the exposed portions become asuspension in suspended state in the peeling solution or sometimes thereare present film flakes in the peeling solution.

Defects of prior art processes are that it is difficult to removecompletely the suspension in a suspended state by filtration even if thefilm flakes may be removed by filtration, and much man-power isnecessary for renewal of filtering area, so that the developing orpeeling solution is changed after used for treating the photosensitivefilm of 0.5 to 0.7 m² /liter and the waste developing or peelingsolution is neutralized in an alkali waste treating apparatus or isfilled in drum cans for disposal. Considering water pollution, muchdisposal cost is necessary.

On the other hand, the production of printed wiring boards is changingfrom the printing method to the so-called photosensitive film method. Asto the photosensitive film method, a so-called alkali-type processwherein the photosensitive film is developed or peeled imagewisely byusing an alkaline aqueous solution is increasing compared with a processwherein the photosensitive film is developed or peeled imagewisely usinga solvent. Thus, the treatment of increased alkali waste with low costis necessary and a demand for development or imagewise peeling ofalkali-type photosensitive film while recycling the developing orpeeling solution becomes stronger.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a process for developing orpeeling an alkali-type photosensitive film by using a regenerateddeveloping or peeling solution wherein a suspension of releasedphotosensitive film suspended therein is removed effectively with lowcost overcoming the defects of the prior art processes. It is anotherobject of this invention to provide an apparatus used for such aprocess.

This invention provides a process for developing or imagewisely peelingan alkali-type photosensitive film which comprises

developing or imagewisely peeling an alkali-type photosensitive filmwith a developing or peeling solution,

taking off the developing or peeling solution containing a releasedphotosensitive film suspension from a developing or peeling device,

introducing one or more reagents and a gas into the developing orpeeling solution to deposit the suspension in floc state,

removing the flocculated deposit in floating state out of the developingor peeling solution, and

recycling the resulting developing or peeling solution to the developingor peeling device.

This invention also provides an apparatus for developing or imagewiselypeeling an alkali-type photosensitive film comprising

a developing or peeling device for developing or peeling an alkali-typephotosensitive film with a developing or peeling solution,

a solution tank for receiving the developing or peeling solutioncontaining a released photosensitive film suspension transported fromthe developing or peeling device,

one or more reagent tanks for storing separately one or more reagentsfor regenerating the developing or peeling solution,

a blower for supplying a gas to the developing or peeling solution, and

one or more floating tanks wherein the released photosensitive filmsuspension suspended in the developing or peeling solution sent from thesolution tank is flocculated with the reagents from the reagent tanksand the gas from the blower and the flocculated deposit in floatingstate is removed from the floating tanks for recycling the resultingdeveloping or peeling solution to the developing or peeling device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventional continuousspray type developing apparatus for alkali-type photosensitive film,

FIG. 2 is a schematic cross-sectional view of an alkali treatmentportion in the continuous spray type developing apparatus, and

FIG. 3 is a schematic cross-sectional view of one example of analkali-type photosensitive film developing apparatus operativelyassociated with a removing device for floated flocculated suspensionaccording to this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

As the device for developing or peeling an alkali-type photosensitivefilm usable in this invention, there are a batch-type device for dippingtreatment of substrates obtained by bonding a photosensitive film andexposing to light, or substrates further treated by etching or plating,and a continuous device wherein these substrates are supplied by aroller conveyor continuously and treated by the spraying method, and thelike.

FIG. 1 is a schematic cross-sectional view of a conventional continuousspray type developing apparatus for alkali-type photosensitive film andFIG. 2 is a schematic cross-sectional view of the alkali treatmentportion in the continuous spray type developing apparatus.

Referring to FIG. 1, a substrate is supplied to the apparatus by manualoperation or automatic operation to the arrowed direction "b" and sentto an outlet with a constant speed successively by a substratetransporting roll 1. In the alkali treatment portion of the apparatus,the substrate is treated by an alkali aqueous solution from sprayers 2to dissolve and release the unexposed portions from the alkali-typephotosensitive film. The substrate is then washed with water from watersprayers 3, treated with a neutralizing treatment solution from sprayers4, followed by rinsing with water from water sprayers 5. Then, thesubstrate is subjected to hydro-extraction by wringer rolls 6, dried ina drying furnace 7 and moved to the arrowed direction "c" by manual orautomatic operation for receiving the photosensitive film to completethe development. In FIG. 1, numeral 8 denotes an alkali aqueous solutiontank, numeral 9 a water tank, numeral 10 a neutralizing solution tank,numeral 11 a developing apparatus frame, and numeral 12 an exhaust duct.

In the case of a continuous spray type peeling apparatus for alkali-typephotosensitive film, the layout is the same as mentioned above.

FIG. 2 is a schematic cross-sectional view of the alkali treatmentportion of the continuous spray type developing apparatus whereinnumeral 1 is the substrate transporting roll, numeral 2 alkali aqueoussolution sprayers, numeral 8 an alkali aqueous solution tank, andnumeral 11 a developing apparatus frame, these being the same as inFIG. 1. FIG. 2 is a cross-sectional view taking a cross-sectionperpendicular to the arrowed direction "b" in FIG. 1 in the alkaliaqueous solution tank 8. The alkali aqueous solution in the alkaliaqueous solution tank 8 is sent to the alkali aqueous solution sprayers2 by a pump 39 through a filter 13. In FIG. 2, numeral 30 denotes apressure gauge, and numeral 31 a valve.

According to the prior art process, there is no regenerating step forthe waste alkali aqueous solution, which results in causing variousproblems mentioned above. According to this invention, such problems aresolved by using the apparatus having a removing device for floatedflocculated suspension of released photosensitive film in the developingor peeling solution as shown in FIG. 3. FIG. 3 is one example of theapparatus according to this invention.

In FIG. 3, the alkali developing or peeling solution containing asuspension of released photosensitive film suspended therein is takenfrom the alkali aqueous solution tank 8 and sent to a solution tank 22by a pump 14. The level of the solution tank 22 is detected by a levelsensor 21 and controlled by a level controller 32 connected to a flowcontrol valve 33. The solution separated by inner dividers 34 and 35 iscirculated and stirred by pumps 15 and 16, respectively. The solutiontank 22 is further equipped with a reagent tank 27 and a reagent pouringpump 19 for providing a reagent for accelerating the deposition of thesuspension of released photosensitive film in floc state and generationand adhesion of bubbles to the deposit.

Examples of such an accelerating reagent is methyl isobutyl carbinol##STR1##

A part of the solution to be treated is taken out of the solution tank22 by a pump 17 and sent to a floating tank 23. The solution to betreated is moved to the arrowed direction "a" through the dividers 34and 35. The dividers 34 and 35 are not always necessary.

A gas is supplied by a blower 29 to the suction side of a pump 17 and areagent is supplied from a reagent tank 28 by a pump 20 also to thesuction side of the pump 17. It is preferable to supply the reagent tothe suction side of the pump 17. The gas and the reagent are mixed withthe solution to be treated with stirring by the pump 17 and introducedinto the floating tank 23.

In the floating tank 23, the solution to be treated is moved to thearrowed direction "d" over a divider 36 and the suspension of releasedphotosensitive film is floated in floc state, which is removed out ofthe tank by a skimmer 25.

As the reagent for depositing and floating the suspension, there can beused cationic polyamine resins.

As the gas for bubbling, there can be used an inert gas such as air andnitrogen. It is preferable to bubble air in an amount of 10 l/min orless so as to form a large number of small bubbles. If the amount is toolarge e.g., more than 10 l/min, the bubbles become larger and will breakat the liquid surface undesirably.

The solution is then passed to a floating tank 24 by a pump 18. In sucha case, the solution from the floating tank 23, the gas from the blower29 and the reagent from the reagent pump 20 are mixed with stirring bythe pump 18. The resulting mixed solution is moved to the arroweddirection "e" over a divider 37 and the remaining suspension floated infloc state is removed by a skimmer 25 out of the tank. In such a case,the dividers 36 and 37 are not always necessary.

The number of floating tank depends on separation efficiency of floatedfloc and may be one or two or more.

It is preferable to connect the bottom of the floating tank 24 and atreated solution tank 26 for storing the treated solution by aconnecting pipe 39 so as to form communicating vessels. The treatedsolution is moved over a divider 38 and returned to the alkali aqueoussolution tank 8 by the level difference between the treated solutiontank and the alkali aqueous solution tank. In such a case, the divider38 is not always necessary.

When a connecting pipe 40 and that of 41 which form communicatingvessels are provided between the solution tank 22 and the floating tank23 and between the floating tank 23 and the floating tank 24, the levelbalance can be controlled even if the balance in supplying amountsbetween the pumps 17 and 18 is lost. The connecting pipes 40 and 41 maybe omitted if another level controlling method is employed.

The taking out amount of the treated solution can be controlled bymaking the divider 38 a dam structure. The treated solution tank 26 isprovided so as to sample the treated solution and to observetransparency, coloring, bubbling, or the like, with the naked eye, butit is not always necessary.

This invention is illustrated by way of the following Examples.

EXAMPLE 1

Using a developing solution (a 2% by weight aqueous solution of Na₂CO₃), an alkali-type photosensitive film (PHT 860 AFT, a trade name,mfd. by Hitachi Chemical Co., Ltd.) was developed until the treatingarea became 0.5 m² /liter and the developing solution in suspensionstate was taken out continuously for regeneration using the apparatus asshown in FIG. 3. Volumes of individual tanks were 80 liters and twofloating tanks were used with a treated solution tank.

Operation conditions were as follows: the taking out amount of thesolution to be treated was 0.05 m³ /hr, the pouring amount of thereagent (FM reagent, methyl isobutyl carbinol) from the tank 27 to 50 mlof the solution to be treated was 0.5% by volume, the pouring amount ofthe reagent (Y reagent, a cationic polyamine resin, mfd. by KyoritsuYuki Kogyo Kenkyusho) from the tank 28 to 50 ml of the solution to betreated was 1% by volume, the blowing amount of air was 10 l/min orless.

The separation efficiency of the suspension was more than 95%.

EXAMPLE 2

Using a peeling solution (a 5% by weight aqueous solution of NaOH), analkali-type photosensitive film (PHT 860 AFT, a trade name, mfd. byHitachi Chemical Co., Ltd.) was treated until the treating area became0.5 m² /liter and the peeling solution in suspension state was taken outcontinuously for regeneration using the apparatus as shown in FIG. 3.Volumes of individual tanks, the number of floating tanks and the likewere the same as in Example 1.

Operation conditions were as follows: the taking out amount of thesolution to be treated was 0.05 m³ /hr, the pouring amount of thereagent (FM reagent) from the tank 27 to 50 ml of the solution to betreated was 0.5% by volume, the pouring amount of the reagent (Yreagent) from the tank 28 to 50 ml of the solution to be treated was 1%by volume, the blowing amount of air was 10 l/min or less.

The separation efficiency of the suspension was more than 95%.

What is claimed is:
 1. A process for developing or imagewisely peeling an alkali-type photosensitive film which comprisesdeveloping or imagewisely peeling an alkali-type photosensitive film with an alkali developing or peeling solution, taking off the developing or peeling solution containing a released photosensitive film suspension from a developing or peeling device, introducing a cationic polyamine resin, methyl isobutyl carbinol and a gas into the developing or peeling solution to effect flocculation of particles of the released photosensitive film suspension, removing the flocculated particles in a floating state from the developing or peeling solution, and recycling the resulting developing or peeling solution to the developing or peeling device.
 2. A process according to claim 1, wherein the gas for floating the deposited suspension is a bubbling air. 